Which aspect is NOT typically under the purview of the Reactor Laboratory?

The aspect that is not typically under the purview of the Reactor Laboratory is the supervision of propulsion plant mechanics. In a nuclear-powered vessel, the Reactor Laboratory is primarily focused on areas directly related to the reactor's functionality and safety. This includes management of reactor plants, control of radiological materials, and chemistry control, all of which are critical to maintaining nuclear safety and ensuring efficient reactor operation.

Management of reactor plants involves overseeing the operational parameters of the reactor to ensure safe and efficient energy production. Control of radiological materials pertains to handling and monitoring substances that emit radiation, ensuring compliance with regulations designed to protect personnel and the environment. Chemistry control is essential for maintaining the integrity of reactor systems and preventing corrosion, maintaining coolant quality, and ensuring safe nuclear reactions.

In contrast, the supervision of propulsion plant mechanics pertains more to the physical maintenance and repair of propulsion systems, which are generally outside the scope of the Reactor Laboratory’s responsibilities. The mechanics focus on the engineering side of the ship's propulsion, while the Reactor Laboratory concentrates on the nuclear aspects and safety protocols associated with the reactor.